Updating VHD disk using Hyper-V on Windows 10 machine

Hi,

I already created VHD disk by first creating new disk, then new VM and installing windows 10 Fall update OS there. Then I syspreped it and got myself VHD ready. The issue is that I can't make this syspreped  VHD work in Azure. We want to spin up Windows 10 Fall client VM there for testing Dev updates. It appears that whatever process we had there before that worked for Creators Update and Anniversary, it doesn't work with FALL update. The issue is that creating of the VM from that VHD that was properly sysprepped fails. I get an error that creation of the VM failed. Timed out.

So I want to update the VHD from Hyper V and not have it generalized. I start the VM and go through the setup account steps, then I click SAVE the VM. Shouldn't that VHD get updated now? I look at the VM and it still shows old time meaning it wasn't updated

Also, if you know why I can't create VM from Fall Sysprep image, please let me know as well.
thank you so much!